content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
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  package com.google.protobuf.util;
  
  import static com.google.common.math.IntMath.checkedAdd;
  import static com.google.common.math.IntMath.checkedSubtract;
  import static com.google.common.math.LongMath.checkedAdd;
  import static com.google.common.math.LongMath.checkedMultiply;
  import static com.google.common.math.LongMath.checkedSubtract;
  
  import com.google.protobuf.Duration;
  import com.google.protobuf.Timestamp;
  import java.text.ParseException;
  import java.text.SimpleDateFormat;
  import java.util.Comparator;
  import java.util.Date;
  import java.util.GregorianCalendar;
  import java.util.Locale;
  import java.util.TimeZone;
  
  /**
   * Utilities to help create/manipulate {@code protobuf/timestamp.proto}. All operations throw an
   * {@link IllegalArgumentException} if the input(s) are not {@linkplain #isValid(Timestamp) valid}.
   */
  public final class Timestamps {
  
    // Timestamp for "0001-01-01T00:00:00Z"
    static final long TIMESTAMP_SECONDS_MIN = -62135596800L;
  
    // Timestamp for "9999-12-31T23:59:59Z"
    static final long TIMESTAMP_SECONDS_MAX = 253402300799L;
  
    static final long NANOS_PER_SECOND = 1000000000;
    static final long NANOS_PER_MILLISECOND = 1000000;
    static final long NANOS_PER_MICROSECOND = 1000;
    static final long MILLIS_PER_SECOND = 1000;
    static final long MICROS_PER_SECOND = 1000000;
  
    /** A constant holding the minimum valid {@link Timestamp}, {@code 0001-01-01T00:00:00Z}. */
    public static final Timestamp MIN_VALUE =
        Timestamp.newBuilder().setSeconds(TIMESTAMP_SECONDS_MIN).setNanos(0).build();
  
    /**
     * A constant holding the maximum valid {@link Timestamp}, {@code 9999-12-31T23:59:59.999999999Z}.
     */
    public static final Timestamp MAX_VALUE =
        Timestamp.newBuilder().setSeconds(TIMESTAMP_SECONDS_MAX).setNanos(999999999).build();
  
    /**
     * A constant holding the {@link Timestamp} of epoch time, {@code 1970-01-01T00:00:00.000000000Z}.
     */
    public static final Timestamp EPOCH = Timestamp.newBuilder().setSeconds(0).setNanos(0).build();
  
    private static final ThreadLocal<SimpleDateFormat> timestampFormat =
        new ThreadLocal<SimpleDateFormat>() {
          @Override
          protected SimpleDateFormat initialValue() {
            return createTimestampFormat();
          }
        };
  
    private static SimpleDateFormat createTimestampFormat() {
      SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss", Locale.ENGLISH);
      GregorianCalendar calendar = new GregorianCalendar(TimeZone.getTimeZone("UTC"));
      // We use Proleptic Gregorian Calendar (i.e., Gregorian calendar extends
      // backwards to year one) for timestamp formating.
      calendar.setGregorianChange(new Date(Long.MIN_VALUE));
      sdf.setCalendar(calendar);
      return sdf;
    }
  
    private Timestamps() {}
  
    private static final Comparator<Timestamp> COMPARATOR =
        new Comparator<Timestamp>() {
          @Override
          public int compare(Timestamp t1, Timestamp t2) {
            checkValid(t1);
            checkValid(t2);
            int secDiff = Long.compare(t1.getSeconds(), t2.getSeconds());
            return (secDiff != 0) ? secDiff : Integer.compare(t1.getNanos(), t2.getNanos());
          }
        };
  
    /**
     * Returns a {@link Comparator} for {@link Timestamp}s which sorts in increasing chronological
     * order. Nulls and invalid {@link Timestamp}s are not allowed (see {@link #isValid}).
     */
    public static Comparator<Timestamp> comparator() {
      return COMPARATOR;
    }
  
    /**
     * Compares two timestamps. The value returned is identical to what would be returned by:
     * {@code Timestamps.comparator().compare(x, y)}.
     *
     * @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if {@code x < y};
     *     and a value greater than {@code 0} if {@code x > y}
     */
    public static int compare(Timestamp x, Timestamp y) {
      return COMPARATOR.compare(x, y);
    }
  
    /**
     * Returns true if the given {@link Timestamp} is valid. The {@code seconds} value must be in the
     * range [-62,135,596,800, +253,402,300,799] (i.e., between 0001-01-01T00:00:00Z and
     * 9999-12-31T23:59:59Z). The {@code nanos} value must be in the range [0, +999,999,999].
     *
     * <p><b>Note:</b> Negative second values with fractional seconds must still have non-negative
     * nanos values that count forward in time.
     */
    public static boolean isValid(Timestamp timestamp) {
      return isValid(timestamp.getSeconds(), timestamp.getNanos());
    }
  
    /**
     * Returns true if the given number of seconds and nanos is a valid {@link Timestamp}. The {@code
     * seconds} value must be in the range [-62,135,596,800, +253,402,300,799] (i.e., between
     * 0001-01-01T00:00:00Z and 9999-12-31T23:59:59Z). The {@code nanos} value must be in the range
     * [0, +999,999,999].
     *
     * <p><b>Note:</b> Negative second values with fractional seconds must still have non-negative
     * nanos values that count forward in time.
     */
    public static boolean isValid(long seconds, int nanos) {
      if (seconds < TIMESTAMP_SECONDS_MIN || seconds > TIMESTAMP_SECONDS_MAX) {
        return false;
      }
      if (nanos < 0 || nanos >= NANOS_PER_SECOND) {
        return false;
      }
      return true;
    }
  
    /** Throws an {@link IllegalArgumentException} if the given {@link Timestamp} is not valid. */
    public static Timestamp checkValid(Timestamp timestamp) {
      long seconds = timestamp.getSeconds();
      int nanos = timestamp.getNanos();
      if (!isValid(seconds, nanos)) {
          throw new IllegalArgumentException(String.format(
              "Timestamp is not valid. See proto definition for valid values. "
              + "Seconds (%s) must be in range [-62,135,596,800, +253,402,300,799]. "
              + "Nanos (%s) must be in range [0, +999,999,999].", seconds, nanos));
      }
      return timestamp;
    }
  
    /**
     * Convert Timestamp to RFC 3339 date string format. The output will always be Z-normalized and
     * uses 3, 6 or 9 fractional digits as required to represent the exact value. Note that Timestamp
     * can only represent time from 0001-01-01T00:00:00Z to 9999-12-31T23:59:59.999999999Z. See
     * https://www.ietf.org/rfc/rfc3339.txt
     *
     * <p>Example of generated format: "1972-01-01T10:00:20.021Z"
     *
     * @return The string representation of the given timestamp.
     * @throws IllegalArgumentException if the given timestamp is not in the valid range.
     */
    public static String toString(Timestamp timestamp) {
      checkValid(timestamp);
  
      long seconds = timestamp.getSeconds();
      int nanos = timestamp.getNanos();
  
      StringBuilder result = new StringBuilder();
      // Format the seconds part.
      Date date = new Date(seconds * MILLIS_PER_SECOND);
      result.append(timestampFormat.get().format(date));
      // Format the nanos part.
      if (nanos != 0) {
        result.append(".");
        result.append(formatNanos(nanos));
      }
      result.append("Z");
      return result.toString();
    }
  
    /**
     * Parse from RFC 3339 date string to Timestamp. This method accepts all outputs of {@link
     * #toString(Timestamp)} and it also accepts any fractional digits (or none) and any offset as
     * long as they fit into nano-seconds precision.
     *
     * <p>Example of accepted format: "1972-01-01T10:00:20.021-05:00"
     *
     * @return A Timestamp parsed from the string.
     * @throws ParseException if parsing fails.
     */
    public static Timestamp parse(String value) throws ParseException {
      int dayOffset = value.indexOf('T');
      if (dayOffset == -1) {
        throw new ParseException("Failed to parse timestamp: invalid timestamp \"" + value + "\"", 0);
      }
      int timezoneOffsetPosition = value.indexOf('Z', dayOffset);
      if (timezoneOffsetPosition == -1) {
        timezoneOffsetPosition = value.indexOf('+', dayOffset);
      }
      if (timezoneOffsetPosition == -1) {
        timezoneOffsetPosition = value.indexOf('-', dayOffset);
      }
      if (timezoneOffsetPosition == -1) {
        throw new ParseException("Failed to parse timestamp: missing valid timezone offset.", 0);
      }
      // Parse seconds and nanos.
      String timeValue = value.substring(0, timezoneOffsetPosition);
      String secondValue = timeValue;
      String nanoValue = "";
      int pointPosition = timeValue.indexOf('.');
      if (pointPosition != -1) {
        secondValue = timeValue.substring(0, pointPosition);
        nanoValue = timeValue.substring(pointPosition + 1);
      }
      Date date = timestampFormat.get().parse(secondValue);
      long seconds = date.getTime() / MILLIS_PER_SECOND;
      int nanos = nanoValue.isEmpty() ? 0 : parseNanos(nanoValue);
      // Parse timezone offsets.
      if (value.charAt(timezoneOffsetPosition) == 'Z') {
        if (value.length() != timezoneOffsetPosition + 1) {
          throw new ParseException(
              "Failed to parse timestamp: invalid trailing data \""
                  + value.substring(timezoneOffsetPosition)
                  + "\"",
              0);
        }
      } else {
        String offsetValue = value.substring(timezoneOffsetPosition + 1);
        long offset = parseTimezoneOffset(offsetValue);
        if (value.charAt(timezoneOffsetPosition) == '+') {
          seconds -= offset;
        } else {
          seconds += offset;
        }
      }
      try {
        return normalizedTimestamp(seconds, nanos);
      } catch (IllegalArgumentException e) {
        throw new ParseException("Failed to parse timestamp: timestamp is out of range.", 0);
      }
    }
  
    /** Create a Timestamp from the number of seconds elapsed from the epoch. */
    public static Timestamp fromSeconds(long seconds) {
      return normalizedTimestamp(seconds, 0);
    }
  
    /**
     * Convert a Timestamp to the number of seconds elapsed from the epoch.
     *
     * <p>The result will be rounded down to the nearest second. E.g., if the timestamp represents
     * "1969-12-31T23:59:59.999999999Z", it will be rounded to -1 second.
     */
    public static long toSeconds(Timestamp timestamp) {
      return checkValid(timestamp).getSeconds();
    }
  
    /** Create a Timestamp from the number of milliseconds elapsed from the epoch. */
    public static Timestamp fromMillis(long milliseconds) {
      return normalizedTimestamp(
          milliseconds / MILLIS_PER_SECOND,
          (int) (milliseconds % MILLIS_PER_SECOND * NANOS_PER_MILLISECOND));
    }
  
    /**
     * Convert a Timestamp to the number of milliseconds elapsed from the epoch.
     *
     * <p>The result will be rounded down to the nearest millisecond. E.g., if the timestamp
     * represents "1969-12-31T23:59:59.999999999Z", it will be rounded to -1 millisecond.
     */
    public static long toMillis(Timestamp timestamp) {
      checkValid(timestamp);
      return checkedAdd(
          checkedMultiply(timestamp.getSeconds(), MILLIS_PER_SECOND),
          timestamp.getNanos() / NANOS_PER_MILLISECOND);
    }
  
    /** Create a Timestamp from the number of microseconds elapsed from the epoch. */
    public static Timestamp fromMicros(long microseconds) {
      return normalizedTimestamp(
          microseconds / MICROS_PER_SECOND,
          (int) (microseconds % MICROS_PER_SECOND * NANOS_PER_MICROSECOND));
    }
  
    /**
     * Convert a Timestamp to the number of microseconds elapsed from the epoch.
     *
     * <p>The result will be rounded down to the nearest microsecond. E.g., if the timestamp
     * represents "1969-12-31T23:59:59.999999999Z", it will be rounded to -1 microsecond.
     */
    public static long toMicros(Timestamp timestamp) {
      checkValid(timestamp);
      return checkedAdd(
          checkedMultiply(timestamp.getSeconds(), MICROS_PER_SECOND),
          timestamp.getNanos() / NANOS_PER_MICROSECOND);
    }
  
    /** Create a Timestamp from the number of nanoseconds elapsed from the epoch. */
    public static Timestamp fromNanos(long nanoseconds) {
      return normalizedTimestamp(
          nanoseconds / NANOS_PER_SECOND, (int) (nanoseconds % NANOS_PER_SECOND));
    }
  
    /** Convert a Timestamp to the number of nanoseconds elapsed from the epoch. */
    public static long toNanos(Timestamp timestamp) {
      checkValid(timestamp);
      return checkedAdd(
          checkedMultiply(timestamp.getSeconds(), NANOS_PER_SECOND), timestamp.getNanos());
    }
  
    /** Calculate the difference between two timestamps. */
    public static Duration between(Timestamp from, Timestamp to) {
      checkValid(from);
      checkValid(to);
      return Durations.normalizedDuration(
          checkedSubtract(to.getSeconds(), from.getSeconds()),
          checkedSubtract(to.getNanos(), from.getNanos()));
    }
  
    /** Add a duration to a timestamp. */
    public static Timestamp add(Timestamp start, Duration length) {
      checkValid(start);
      Durations.checkValid(length);
      return normalizedTimestamp(
          checkedAdd(start.getSeconds(), length.getSeconds()),
          checkedAdd(start.getNanos(), length.getNanos()));
    }
  
    /** Subtract a duration from a timestamp. */
    public static Timestamp subtract(Timestamp start, Duration length) {
      checkValid(start);
      Durations.checkValid(length);
      return normalizedTimestamp(
          checkedSubtract(start.getSeconds(), length.getSeconds()),
          checkedSubtract(start.getNanos(), length.getNanos()));
    }
  
    static Timestamp normalizedTimestamp(long seconds, int nanos) {
      if (nanos <= -NANOS_PER_SECOND || nanos >= NANOS_PER_SECOND) {
        seconds = checkedAdd(seconds, nanos / NANOS_PER_SECOND);
        nanos = (int) (nanos % NANOS_PER_SECOND);
      }
      if (nanos < 0) {
        nanos =
            (int)
                (nanos + NANOS_PER_SECOND); // no overflow since nanos is negative (and we're adding)
        seconds = checkedSubtract(seconds, 1);
      }
      Timestamp timestamp = Timestamp.newBuilder().setSeconds(seconds).setNanos(nanos).build();
      return checkValid(timestamp);
    }
  
    private static long parseTimezoneOffset(String value) throws ParseException {
      int pos = value.indexOf(':');
      if (pos == -1) {
        throw new ParseException("Invalid offset value: " + value, 0);
      }
      String hours = value.substring(0, pos);
      String minutes = value.substring(pos + 1);
      return (Long.parseLong(hours) * 60 + Long.parseLong(minutes)) * 60;
    }
  
    static int parseNanos(String value) throws ParseException {
      int result = 0;
      for (int i = 0; i < 9; ++i) {
        result = result * 10;
        if (i < value.length()) {
          if (value.charAt(i) < '0' || value.charAt(i) > '9') {
            throw new ParseException("Invalid nanoseconds.", 0);
          }
          result += value.charAt(i) - '0';
        }
      }
      return result;
    }
  
    /** Format the nano part of a timestamp or a duration. */
    static String formatNanos(int nanos) {
      // Determine whether to use 3, 6, or 9 digits for the nano part.
      if (nanos % NANOS_PER_MILLISECOND == 0) {
        return String.format(Locale.ENGLISH, "%1$03d", nanos / NANOS_PER_MILLISECOND);
      } else if (nanos % NANOS_PER_MICROSECOND == 0) {
        return String.format(Locale.ENGLISH, "%1$06d", nanos / NANOS_PER_MICROSECOND);
      } else {
        return String.format(Locale.ENGLISH, "%1$09d", nanos);
      }
    }
  }
  